Nanotube transistors make memory

June 18/25, 2003

Researchers from the Samsung Advanced Institute
of Technology in Korea and the Chonbuk National University in Korea have
laid the groundwork for making nonvolatile computer memory out of carbon
nanotubes.

Nanotubes are rolled-up sheets of carbon atoms that can be smaller
than a nanometer across, or about the width of a row of 10 hydrogen atoms.
Nonvolatile memory retains information even when its power is turned off.
The researchers' method could lead to very high capacity nonvolatile memory.

The researchers fashioned a transistor from a carbon nanotube, and
topped it with a layer of silicon nitride sandwiched between layers of silicon
oxide. The oxide-nitride sandwich can hold an electric charge, and the transistor
can induce or drain the charge. The presence and absence of electric charges
can represent the 1s and 0s of computing.

Arranged vertically, the storage devices could be used to make nonvolatile
memory that stores 200 gigabits per square inch, according to the researchers.
This is about 200 times the capacity of today's memory chips.

The device could be used in practical applications in 10 to 15 years,
according to the researchers. The work appeared in the January 13, 2003
issue of Applied Physics Letters.